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Biomedical subjects

R U Peter

Publications and source records attributed to R U Peter.

At least 109 records · Page 6Linked to original sources
PubMed1998

Nitric oxide inhibits tissue factor synthesis, expression and activity in human monocytes by prior formation of peroxynitrite.

OBJECTIVE: Nitric oxide (NO) has antithrombotic properties by regulating platelet function, whereas direct effects on plasmatic coagulation are rarely described. In sepsis and inflammation, when synthesis of NO, oxygen radicals and toxic metabolites is crucial, the expression of tissue factor (TF) on monocytes stimulated by lipopolysaccharides (LPS) induces intravascular coagulation. This study was performed to examine the influence of NO and the NO-dependent metabolite peroxynitrite on LPS-induced TF expression and activity in human monocytes. DESIGN: Experimental study. SETTING: Laboratory for cell biology. METHODS: Human peripheral blood mononuclear cells were isolated from buffy coats by gradient centrifugation. The NO-releasing compounds SIN1 and NOC18 were used under different conditions. TF antigen was assayed by flow cytometry, and its activity by a clotting assay. TF-mRNA was measured by reverse transcriptase polymerase chain reaction (RT-PCR-ELISA). MEASUREMENTS AND RESULTS: Whereas NOC18, a pure NO donor, had no effect, SIN1, releasing both NO and superoxide (O2-), reduced TF expression and activity in a dose- and time-dependent manner; superoxide dismutase (SOD) reversed the SIN1-mediated effect. Adding the O2(-)-deliberating system hypoxanthin/xanthin oxidase (which had no significant effect per se) to NOC18, or using the NO and O2- reaction product peroxynitrite resulted in a reduction of TF expression. RT-PCR-ELISA indicated upregulation of TF-mRNA by SIN1 with a peak at 500 microM; higher doses had less effect. CONCLUSION: These data demonstrate an influence of NO on LPS-induced TF expression in monocytes by prior formation of peroxynitrite; furthermore, the balance between NO and O2- seems to play a crucial role.

Dose-Response Relationship, Drug↗
PubMed1998

Providing dermatological photographs using the multimedia extension of the international computer database for radiation accident case histories.

The World Health Organisation (WHO) Radiation Emergency Medical Preparedness (REMPAN) centres have built up the International Computer Database for Radiation Accident Case Histories (ICDREC) to document the medical treatment of acute radiation syndrome (ARS) patients. Images play an increasing role as complementary information beside text and numerical data in medicine. In particular, retrieval and display of digitised skin photographs serve to improve patient care, medical education and scientific analysis concerning the cutaneous radiation syndrome (CRS). The ICDREC has been built up as a client/server system. Particular focus has been set on using commercial off-the-shelf software components. All the medical data including the multimedia data are stored in a relational database system. The database can be accessed by inexpensive personal computers in the physician's workplace. Retrieval of one photograph via local area network (LAN) requires approximately 3 s. Authorised institutions can access the database via the Internet. The current state of the ICDREC multimedia component is illustrated with the skin lesion treatment of a Chernobyl patient. An example is given on how the workflow in a dermatology department is supported by the ICDREC.

Databases, Factual↗
PubMed1998

Dermatoscopy and high frequency sonography: two useful non-invasive methods to increase preoperative diagnostic accuracy in pigmented skin lesions.

Dermatoscopy and high frequency sonography have recently been combined to increase diagnostic preoperative accuracy in the treatment of pigmented skin lesions. In this monocentric study 80 patients with pigmented skin lesions were evaluated clinically, by dermatoscopy, and 20 MHz-sonography followed by dermatohistopathological evaluation; 39 malignant melanomas, 37 common nevi, 3 dysplastic nevi, and 1 nevus Spitz were diagnosed histologically. In 72 of the 80 cases (91.3%) dermatoscopical diagnoses were confirmed by histopathology, compared to only 79% correct clinical diagnoses. For the mere clinical diagnosis of melanoma sensitivity was 79%, specificity was 78% and diagnostic accuracy was 65%. All diagnostic values increased by dermatoscopy: sensitivity reached 90%, specificity was 93%, and diagnostic accuracy was 83%. In order to determine tumor thickness preoperatively tumor thickness was measured by 20 MHz sonography. The correlation of tumor thickness between histometric and sonographic results was determined for nevi (r = 0.93) and melanoma (r = 0.95); 74.3% of melanomas were diagnosed correctly within an 0.2 mm range. Regarding the clinical important limit of 1 mm tumor thickness, 87.2% were diagnosed in accordance with histometric evaluation. An increase of 18% in diagnostic accuracy by dermatoscopy and 87.2% of correctly diagnosed cases of tumor thickness of malignant melanoma by high frequency sonography clearly demonstrate that these methods should be considered standard procedures in the diagnosis of pigmented skin lesions and will facilitate the decision on necessary surgical treatment.

Humans↗
PubMed1998

A multimedia database for dermatology.

The World Health Organisation (WHO) Radiation Emergency Medical Preparedness (REMPAN) centres have built up the International Computer Database for Radiation Accident Case Histories (ICDREC) to document the treatment of acute radiation syndrome (ARS) patients. Radiation induced skin lesions may cause severe late effects in radiation accident patients. Dermatological multimedia documentation is included into the ICDREC. In particular, retrieval and display of digitised skin photographs and medical reports serves to improve patient care, medical education, and scientific analysis concerning the cutaneous radiation syndrome (CRS). The database has been built up as a client/server system. A particular focus has been set on using commercial off-the-shelf software components. The medical data including the multimedia data are stored in a relational database system. The database can be accessed by inexpensive personal computers in the dermatologist's workplace. Authorised institutions can access the database via the Internet. Retrieval of one skin photograph via local area network (LAN) requires approximately 3 seconds. The current state of the application is illustrated with the skin lesion treatment of a Chernobyl patient. An example is given on how to access the ICDREC from a dermatologist's desktop personal computer. The discussion focuses on the advantages of storing the textual and pictorial data in one central database to be accessed from different care centres and how the results can be generalised for medical multimedia information systems.

Dermatology↗
PubMed1997

[Anogenital condylomata acuminata, mucocutaneous candidiasis, vitiligo, keratopathy and primary hypoparathyroidism in an autoimmune polyglandular syndrome type 1].

HISTORY: 6 months before admission a 21-year-old woman had developed anogenital condylomata acuminata (CA). Since early childhood she had been treated for primary hypoparathyroidism (PHPT) and recurrent mucocutaneous candidiasis. 5 years before admission corneal clouding had caused visual impairment. Recently, mainly truncal vitiligo with occipital poliosis had developed. INVESTIGATIONS: PHPT was confirmed (parathormone level 7.7 mg/l). In addition, liver transaminases were raised (GOT 105.8 U/l, GPT 145.6 U/l, gamma-GT 56.8 U/l), pointing to noninfectious hepatitis. An ACTH stress test could not exclude manifest adrenocortical insufficiency, and thyroid function was also normal. The Merieux Multitest indicated an anergy. DIAGNOSIS, TREATMENT AND COURSE: The constellation of test results suggested autoimmune polyglandular syndrome type I. The condylomata were treated by electrocautery and the intestinal candidiasis with amphotericin B suspension. Calcitriol capsules, 0.5 microgram, and calcium gluconate or lactate, 500 and 300 mg respectively, 3 times daily each, were given for the PHPT. CONCLUSION: This case demonstrates a complex syndrome which can be recognized early by simple clinical tests. Early diagnosis prevents possible life-threatening complications.

Adult↗
PubMed1997

Radiation lentigo. A distinct cutaneous lesion after accidental radiation exposure.

BACKGROUND: Accidental exposure of skin to ionizing radiation leads to long-term alterations such as fibrosis, keratosis, and teleangiectasias. Also, noncharacteristic hyperpigmentation and hypopigmentation may be noted. OBSERVATIONS: A distinct lesion is described on the calves of a white male survivor of the 1986 nuclear accident at Chernobyl, Ukraine. Several years after the accident at Chernobyl, characteristic pigmented macules developed in the areas of skin that had previously been exposed to ionizing radiation: there was a marked, sharply demarcated lentiginous hyperpigmentation of epidermal and basal keratinocytes and melanocytes, as well as an increase in the number of melanocytes. No cellular atypia was noted. CONCLUSIONS: This case demonstrates the potential of high single doses of ionizing radiation to induce pigmented lesions with similar clinical and histological features as they have been described after exposure to natural UV radiation or radiation from a tanning bed or sunlamp or after therapy with oral psoralen with long-wave UV-A radiation (PUVA), described as solar, tanning bed, and PUVA lentigines. The absence of cellular atypia may account for a favorable prognosis and enables clear distinction from more serious diagnoses such as lentigo maligna melanoma.

Humans↗
PubMed1997

[Bullous skin reactions after soft roentgen radiotherapy of HIV-associated Kaposi sarcomas].

Fractionated irradiation with X-rays or megavoltage is an important therapeutic option in the palliative treatment of Kaposi's sarcoma. We report on three HIV patients demonstrating bullous cutaneous eruptions in the irradiation field. Three homosexual men (age 45-60 y) stage of disease CDC 3C, were treated with fractionated soft X-rays with the scheme conventionally used by us (total dose 30 Gy, single doses 3 Gy). Immediately to three days after completion of treatment large blisters appeared within the irradiation field, resolving after 2-4 weeks, leaving post-inflammatory hyperpigmentation. The cause of this rare reaction to soft X-ray therapy, potentially suggesting an individually altered radiation sensitivity, is so far unknown. Controlled prospective studies applying different fractionation schemes will be necessary to better elucidate this issue.

HIV Infections↗
PubMed1997

Sonographic determination of cutaneous and subcutaneous fibrosis after accidental exposure to ionising radiation in the course of the Chernobyl nuclear power plant accident.

Chronic cutaneous lesions in eight of 15 survivors of the Chernobyl nuclear energy plant accident presenting with clinical features of cutaneous radiation fibrosis were examined 6 years after exposure using high-frequency ultrasound. In all patients, lesional skin was examined using both the B- and A-modes. Similar phenomena were found in all patients. The corium was increased in thickness as well as density compared to normal skin. The increase in density was seen not only in the medium strata but also particularly at the border between corium and subcutaneous tissue. Within the subcutaneous tissue proper, isles of echo-rich spots were prominent. The number and width of echo signals in the subcutaneous tissue were increased, representing the sonographic correlate of subcutaneous fibrotic trabeculae. The thickness of epidermis plus corium was increased by more than 50% and was even doubled in some cases. According to the present findings obtained from patients with very severe exposure to ionising radiation, ultrasound analysis of cutaneous and subcutaneous radiation fibrosis shows a characteristic picture. Moreover, it was demonstrated that quantitative assessment of skin thickness is possible. As the method is simple and noninvasive, repeated examinations are possible. This provides the basis for monitoring possible treatment effects and efficient follow-up in these chronically progressive clinical conditions after exposure to ionising radiation.

Adult↗
PubMed1997

Induction of interleukin 6 by ionizing radiation in a human epithelial cell line: control by corticosteroids.

The cutaneous radiation syndrome after therapeutic or accidental exposure of human skin to ionizing radiation (IR) is accompanied by inflammatory processes which are controlled partly by proinflammatory cytokines. Besides tumour necrosis factor (TNF)-alpha and interleukin (IL)1, the pluripotent cytokine IL-6 belongs to the key mediators of inflammation. So far, there are no reports about the regulation of IL-6 by IR in epidermal cells. As an in vitro model to study the effects of IR on IL-6 gene expression, we treated the human epithelial HeLa cell line with different single X-ray doses between 1 and 20 Gy. Twenty-four hours after irradiation the IL-6 secretion was dose-dependently enhanced as measured by ELISA. At the transcriptional level, a slight increase of IL-6 transcripts was already detectable 1 h after irradiation, with maximum levels at 2 h, and a decline to baseline levels between 8 and 24 h. Addition of the transcriptional inhibitor actinomycin D inhibited the inducibility of IL-6 mRNA by TPA and IR. As the IL-6 promoter contains multiple binding sites for activated glucocorticoid receptors within the 5' regulatory region, the potential modulation of IL-6 expression by the corticosteroids hydrocortisone, dexamethasone and mometasone furoate was included in our study to modify the radiation-induced stress response. All corticosteroids applied could efficiently downregulate TPA- or radiation-induced IL-6 expression on both gene expression and protein levels. Mometasone furoate, followed by dexamethasone, was found to be most effective at low concentrations (1 nM), whereas hydrocortisone had to be applied at about 100-fold higher concentrations to achieve comparable inhibition. This experimental model is aimed at understanding the molecular circuits following IR, and thus to provide a basis for the treatment of radiation effects in skin.

Adrenal Cortex Hormones↗
PubMed1997

Ionizing radiation induces, via generation of reactive oxygen intermediates, intercellular adhesion molecule-1 (ICAM-1) gene transcription and NF kappa B-like binding activity in the ICAM-1 transcriptional regulatory region.

Ionizing radiation produces reactive oxygen intermediates in mammalian tissues and may serve as a model system for the investigation of the biologic effects of free radicals. We have previously shown that the adhesion molecule ICAM-1 is induced by ionizing radiation, and here we have investigated the molecular mechanisms responsible. ICAM-1 mRNA and cell surface expression was induced in HeLa and HaCaT cells after exposure to ionizing radiation. This induction was blocked by preincubation with the antioxidants PDTC and N-acetyl cysteine. ICAM-1 promoter activity was assessed by transiently transfecting HeLa cells with CAT-reporter gene constructs containing sequential ICAM-1 5' deletions. ICAM-1 5' fragments -1162/+1 (relative to the transcription start site) and -277/+1 displayed increased promoter activity when cells were exposed to ionizing radiation, but no induction was seen in a -182/+1 construct associating positions -277 to around -182 with inducibility by ionizing radiation. Nuclear extracts from HaCaT cells were tested in mobility shift assays using an NF kappa B-like binding site of the ICAM-1 5' region (positions -186/-177). There was marked enhancement of DNA-protein complex forming in extracts from irradiated versus untreated cells. Incubation of cells with antioxidants prior to irradiation prevented the radiation-dependent increase in complex formation. We conclude that reactive oxygen intermediates are involved in ICAM-1 induction by ionizing radiation. The ionizing radiation-induced, antioxidant-inhibitable binding at the ICAM-1 NF kappa B-like binding site is consistent with the view that NF kappa B is a pro-oxidant transcription factor.

Binding Sites↗
PubMed1997

Transcriptional regulation of the human IL5 gene by ionizing radiation in Jurkat T cells: evidence for repression by an NF-AT-like element.

Eosinophilia is often observed in patients with parasitic infections and atopic diseases like allergic asthma and atopic dermatitis. Additionally, it is a typical feature of the inflammatory reaction after therapeutic and accidental exposure to ionizing radiation. This uniquely specific phenomenon regulated by the cytokine interleukin 5 (IL-5) suggests specific control for IL5 gene expression. In this study, we generated promoter-CAT constructs containing different human IL-5 promoter regions spanning from positions -507 to +43. Transfection experiments in Jurkat T cells revealed that the promoter sequence from -57 to +43 was required for constitutive and inducible IL-5 promoter activity. Low baseline CAT activity could be enhanced by treatment with phenylmercuric acetate (PMA) or the combination of PMA and calcium ionophore. The promoter region between positions -97 and +43 showed responsiveness to low-dose X rays. Electrophoretic mobility shift assays demonstrated that the region from -117 to -97 was responsive to irradiation. Transcription factors specifically bound to this sequence showed a dose-dependent response to single doses of X rays between 1 and 8 Gy. Competition analysis indicated that the protein-DNA complexes at this region were related to the nuclear factor of activated T cells (NF-AT). Further confirmation was obtained by the addition of specific antibodies into protein-DNA reactions. For the first time, we have demonstrated that specific DNA binding of NF-ATp at the promoter region from -117 to -97 is involved in transcriptional regulation of the human IL5 gene in response to ionizing radiation.

DNA↗
PubMed1996

[The treatment of cutaneous radiation-induced fibrosis with pentoxifylline and vitamin E. An empirical report].

BACKGROUND: Radiation fibrosis represents a severe complication of radiation therapy; standardized treatment protocols are lacking so far. Surgical excision rarely results in complete healing. PATIENT AND METHODS: We report on a 58-year-old female patient who developed a squamous cell carcinoma within the fibrotic area of the irradiation field on the right chest, resulting from a radiotherapy following mastectomy for breast cancer 17 years ago. After surgical excision of the carcinoma a combined treatment with pentoxifylline tablets (3 x 400 mg/d p.o.) and vitamin-E capsules (1 x 400 mg/d p.o.) was initiated. Skin thickness was quantified by 20 MHz-ultrasound before and during treatment. RESULTS: The patient noted an increasing improvement of the condition of the affected skin starting from 4 months. A continuing decrease of skin thickness as documented by 20 MHz-ultrasound could be demonstrated from the 6th month on. The treatment was tolerated well, no side effects were observed. CONCLUSION: The data indicate a beneficial therapeutic effect of pentoxifylline and vitamin E on radiation-induced fibrosis. Little is known about the mechanism of action of this combined treatment protocol including pentoxifylline and vitamin E. Controlled clinical trials should be performed to confirm this observation.

Breast Neoplasms↗
PubMed1995

Human malignant melanoma. A genetic disease?

BACKGROUND: Human hereditary malignant melanoma, comprising 5% of all cases of malignant melanoma, occurs in association with other malignancies, predominantly in families with dysplastic nevus syndrome. Additionally, higher incidences of malignant melanoma have been reported in individuals with genetic disorders such as ataxia telangiectasia and xeroderma pigmentosum. The results and observations as reported in the literature on the involvement of oncogenes and chromosomal aberrations in the development of malignant melanoma are reviewed and compared with the authors' own experimental and clinical experience. RESULTS: Numerous chromosomal regions, as on chromosomes 1 and 9, were altered. The long arm of chromosome 6 was affected in 60% of melanomas. Introduction of a normal copy of chromosome 6 resulted in loss of tumorigenicity in vitro. True melanoma genes were evident in two animal models: the Sinclair swine and the teleost fish Xiphophorus. In the Xiphophorus system, the crossing-conditioned elimination of a tumor suppressor gene led to the uncontrolled activity of a dominantly acting oncogene in certain hybrids. The causative oncogene, Xmrk, encodes a receptor tyrosine kinase closely related to human epidermal growth factor receptor (EGFR). Among the numerous studied human oncogenes, mutations in the extensively investigated ras family are the result rather than the cause of malignant transformation. High expression of nuclear oncogenes simply may be a common feature of rapidly dividing cells. The receptor tyrosine kinase EGFR may be involved in late stage melanoma; the human exon with homology to Xmrk shows elevated transcription levels in 80% of human melanoma metastases. Deletions of the tumor suppressor gene MTS 1 may be important for melanoma formation, whereas deletions of p53 appear to be of minor relevance. CONCLUSION: Scientific progress in treating and diagnosing malignant melanoma will largely depend on experimental approaches to define relevant genetic changes by functional analysis rather than descriptive phenomenology and correlative observations.

Animals↗
PubMed1995

Chromosome painting in highly irradiated Chernobyl victims: a follow-up study to evaluate the stability of symmetrical translocations and the influence of clonal aberrations for retrospective dose estimation.

Follow-up fluorescence in situ hybridization (FISH) measurements of symmetrical translocations were performed in peripheral blood lymphocytes from 12 highly irradiated victims of the Chernobyl nuclear power plant accident biannually, between September 1991 and July 1994, to investigate the persistence of these aberration type with time post-exposure. Translocations were determined using biotin-labelled painting DNA probes for human chromosomes 1, 4 and 12 and a digoxigenin-labelled alpha-satellite pancentromeric DNA probe. In 11 of 12 cases the translocation frequencies remained fairly constant during the observation period, which allows to generate comparable dose estimates on the various sampling times. In one case (no. 9) the existence of a cell clone containing the consistent chromosome rearrangement t(1;13) (q25;q14) was identified using FISH in rehybridized slides with a digoxigenin-labelled painting DNA probe for chromosome 13 and a separate G-banding analysis. To obtain reliable dose estimates, total translocation frequency has to be corrected for the high contribution (16.5-23.5%) of this clonal translocation.

Accidents↗